Display device with light guide having polarizing material with regions converted into isotropic material

Abstract

Transflective display device has an optical waveguide commonly known as a light guide. The guide includes areas having a chiral nematic structure which splits light coming in from aside into two light beams having a mutually opposite circular polarization. Polarization splitting is achieved at the interface of the areas having the chiral nematic structure.

What is claimed is:  
     
       1. A front-lighted reflective display device comprising an image display panel having a first substrate which is provided with light-reflecting electrodes at the area of pixels, an illumination system comprising an optical waveguide of an optically transparent material having an exit face facing the image display panel and a plurality of end faces, at least one of said end faces being an entrance face for light, while light can be coupled into said end face of the optical waveguide, wherein the optical waveguide is present between the image display panel and a circular polarizer, and the optical waveguide comprises polarizing means for substantially circularly polarizing light entering the polarizing means, said polarizing means including anisotropic material and locally converted regions of isotropic material. 
     
     
       2. A front-lighted reflective display device as claimed in  claim 1 , wherein the image display panel comprises a second light-transmissive substrate and electro-optical material between the two substrates. 
     
     
       3. A front-lighted reflective display device as claimed in  claim 1 , wherein the polarizing means comprise a chiral nematic liquid crystal material. 
     
     
       4. A front-lighted reflective display device as claimed in  claim 3 , wherein the polarizing means comprise a patterned chiral nematic polymer network in the optical waveguide. 
     
     
       5. A front-lighted reflective display device as claimed in  claim 1 , wherein the polarizing means comprise a chiral nematic polymer network. 
     
     
       6. A front-lighted reflective display device as claimed in  claim 5 , wherein the polarizing means comprise a patterned chiral nematic polymer network in the optical waveguide. 
     
     
       7. A front light comprising an optical waveguide of optically transparent material and a plurality of end faces, at least one of said end faces being an entrance face for light, while light can be coupled into said end face of the optical waveguide, wherein the optical waveguide comprises polarizing means for circularly polarizing light entering the polarizing means, said polarizing means including anisotropic material and locally converted regions of isotropic material. 
     
     
       8. A front light as claimed in  claim 7 , wherein the polarizing means comprise a chiral nematic crystal material. 
     
     
       9. A front light as claimed in  claim 8 , wherein the polarizing means comprise a patterned chiral nematic polymer network in the optical waveguide. 
     
     
       10. A front light as claimed in  claim 7 , wherein the polarizing means comprise a chiral nematic polymer network. 
     
     
       11. A front light as claimed in  claim 10 , wherein the polarizing means comprise a patterned chiral nematic polymer network in the optical waveguide. 
     
     
       12. A method of manufacturing a front light comprising polarizing means for circularly polarizing the entering light, wherein a surface of a transparent body is provided with a layer of a chiral nematic material which is locally converted into isotropic material. 
     
     
       13. A method of manufacturing a front light comprising polarizing means for circularly polarizing the entering light, wherein a surface of a transparent body is provided with a layer of a chiral nematic material which is locally converted into chiral nematic material having a reflection band outside the visible range.